Stability of Benney-Luke line solitary waves in 2D.

The $2$D Benney-Luke equation is an isotropic model which describes long water waves of small amplitude in $3$D whereas the KP-II equation is a unidirectional model for long waves with slow variation in the transverse direction. In the case where the surface tension is weak or negligible, linearly stability of small line solitary waves of the $2$D Benney-Luke equation was proved by Mizumachi and Shimabukuro [Nonlinearity, 30 (2017), 3419--3465]. In this paper, we prove nonlinear stability of the line solitary waves by adopting the argument by Mizumachi ([Mem. Amer. Math. Soc. no. 1125], [Proc. Roy. Soc. Edinburgh Sect. A., 148 (2018), 149--198] and [arXiv:1808.00809]) which prove nonlinear stability of $1$-line solitons for the KP-II equation.